The capability for vivo monitoring of regional as well as global oxygen distribution within organs and tissues is of fundamental importance as an indicator of physiologic/metabolic status or well being. Now, unique opportunities for definitive evaluation of novel as well as established medical applications of the perfluorocarbon (PFC) blood substitute materials are possible through utilization of stable fluorine-19 magnetic resonance techniques. These extremely sensitive, noninvasive methodologies may be used to investigate the in vivo properties of PFCs. Of significance is the high oxygen solubility in the PFGs coupled with the intrinsic paramagnetic property of oxygen which strongly affects the spin relaxation time Tl. This mechanism now allows in vivo oxygen sensitive imaging in specific tissues, organs, vascular compartments and other anatomical spaces containing PFCs. The proposed research is designed to test the hypothesis that clinically practical levels of perfluorocarbon (PFC) emulsions when added to or substituted for blood will allow accurate, reproducible quantitation of pO2 in regions of PFC distribution. The fundamental objectives of the proposed research are to evaluate methodologies for non-invasive quantitation of pO2 in vivo over relevant physiological ranges for designed tissues using fluorocarbon F-19 magnetic resonance imaging techniques and to document the accuracy attainable. The PFCs employed will be restricted to: (a) those which appear to have potential commercial availability in emulsion form including FC-43 (oxypherol ET). F-decalin and F-tripropylamin (Fluosol DA), and perfluorooctylbromide (PFCS Emulsion-T); and, (b) other specific PFC's (or derivatives of those listed above) available to the investigators for emulsification and study. The hypothesis testing will be directed toward two anatomic regimes: (a) static accumulations of PFC's in organs (phantoms; liver as the in vivo specific site in various animal models); and (b) vascular environments (flow phantoms; major vessels and blood pools in the porcine model).